1. Field of the Invention
The present invention relates to a three dimensional weight bearing structure enclosing two or three tubes with a maximum ratio of interior tube cross sectional area to overall cross sectional area, while minimizing overall structure mass and structural profile size to ease integration in a diversity of applications and locations.
The structure needs to have a high transverse load bearing capacity and stiffness to afford long spans. Further benefit is provided if the structure supporting the tubes is itself enclosed efficiently to allow a temperature controlled environment to the transport tubes and it is advantageous for the structure to be partially transparent in case the transport tubes themselves are transparent.
2. Prior Art
Trusses are generally designed as fully constrained and stationary 2 dimensional structures supporting one major load type, resisting a gravitational load, over a distance between supporting points, a span. Most trusses are composed of elements that carry stress along their principal axis as tensile or compressive loads between nodes or points of connection. Engineered structures such as I-beams are designed to resist bending and tubes are designed to carry torsional loads. There are applications such as torsion bar automobile suspensions that use torsional stresses to manage vertical, gravitational loads, translating the vertical force into a torsional stress, but these are considered machines and trusses generally, do not currently use torsional stress to manage vertical loads
Three dimensional trusses or frames in use include the space truss formed by connected tetrahedron frames or shapes, Geodetic aircraft frames and the Iso-truss consisting at least in part of straight elements helically wound about a longitudinal axis. Three dimensional trusses are designed to handle multidimensional loads, or to handle a principal load, such as gravity, using a solution outside of the plane formed by the gravitational load over a span.